Method of preparing metallic molds for casting metal



Patented June 23,1931 I UNITED STATES FRANK S. CABLILE, OF ABIH'G'TON PENNSYLVANIA METHOD PREPARING METALLIC HOLDS FOB CASTING METAL No Drawing.

This invention relates to the art of casting metal and is particularly directed to the preparation of metallic molds for casting metal. Although the invention ma be generally applied, I have found it 0 specific value in the production of soft metal castings such for instance as storage battery plates.

It has been the practice to prepare the molds for receiving the molten metal by dustin them with talcum powder or the like or smo 'ng them to form a coating of finely divided carbon, for the purposes of preventing the solidified castmg from sticking to the mold, thermally insulating the molten metal to secure proper flowing into the corners and interstices of the mold and allowing the escape of air while the metal is flow- 1n The objects of this invention are to provide an improved method of preparing this type of molds for casting, to prevent the solidified cast from adhering to the mold, to secure sharp castings, to vent the mold, to lower the casting temperature, to increase the life of a prepared mold, to facilitate repreparing a mold, to overcome the defects of prior practice and to generally improve the art of casting metal in metal molds. I have discovered-that if a mold is covered with a coating of fine blisters-a surfaceis produced which materially facilitates the production of desirable castings. I have experimented with ap lying a varnish froth, of applying various orms of varnish and then heating the mold to form the blisters, .of applying varnishes admixed with pre-' formed blistered substances, butI find that the bestway to produce my desired result is 40 'to apply a varnish like material while the mold is maintained at a temperature suflicientlg high to causethe varnish to blister as it ries. v

Although a number ofsubstances may be used as the said varnish like material, such as nonaqueous solutions of resins, gums, nitrocellulose, pitch or tar, or aqueous solutions of gelatin, casein, albumen, gluten and the like, I have-found'that a varnish made by admixing evaporated cellulose pulp 7 Application filed August 2, 1980. Serial R0. 472,768.

waste liquor and water possesses advantages over the other substances which have come within the range of my experiments. The cellulose pulp waste liquor may be evaporated to dryness and o ten appears on the market in the form of flour which form Iprefer to employ although it should be understood that the degree of evaporation is immaterial so long as the concentration of the dry material in my finished var- 80 nish remains the same. Although the amount of water used to form my varnish may be varied over a wide range, I have concluded that the best admixture for my purpose is made by dissolving one pound 66 of the evaporated cellulose pulp waste liquor in the form of flour in nine pounds of water.

To carry out my invention, I heat the mold which is usually of steel, although it 70 may be made of brass or other suitable metal, to a temperature sufliciently high to cause the applied varnish to blister. When the cellulose pulp waste li uor varnish is used the temperature should 450 F. more 7 of less. I then apply my varnish.

This ma be accompllshed by di ping, brushin ow-coating or spraying. have found t at superior results are obtained b spraying. I have found that about one ga lon of varnish will cover about 200 uare feet of mold surface when a coating 0 the proper thiclmess is applied. As soon as the varnish touches the heated surface it at once 7 forms minute blisters. 85.

The -mold may now be used for casting, however, I have found that better results are obtained by first breaking many of the blisters before using the mold. This may be accomplished in any manner but I have found that simply lightly brushing the surface accomplishes the result.

It is evident from my description that In process enables me to produce a mold whic differs from previousmolds in that it has a nonmetallic casting surface of minute blisters or of broken blisters depending on whether or not the final step in my process has been performed.

When my processed mold is used for casting, I have found that the metal may be sharp accurate castings. This effect is aug-- mented by the property of my coating in allowing the entrapped air to escape to the vents of the mold. Heretofore much trouble has been encountered by coatings plugging up the said vents but the use of my coating does not produce this condition and thus this trouble is overcome. It has been the custom to coat a mold after each cast but this is not necessary where my coating is employed as I have found one treatment suflicient for making two hundred or more castings. When the time comes however, for recoating the molds, all that is required is to wipe off my coating with water whereupon, due to its solubility in water, it is entirely removed, leaving a surface ready for re-treating.

Although my molds produce very sharp castings, I have noted that the solidified castings do not adhere and are therefore very easily removed, thus saving much time and trouble. This advantage coupled with the lasting properties of my coating and the ease and speed of its application enables molds to be operated by hand or machine at high speed and thus further enable the makin of castings at lower cost.

IIaving thus described my invention, I claim: I

1. The method of preparing metallic molds for casting metal consisting in applying to the said mold a varnish like coating and heating the said mold to a temperature sufficiently high to cause the said coating to blister.

2. The method of preparing metallic molds for casting metal consisting in applying to the said mold a varnish like coating and heating the said mold to a temperature sufficiently high to cause the said coating to blister while the said coating is drying.

3. The method of preparing metallic molds for casting metal consisting in coating the said mold with a varnish like ma terial while the said mold is maintained at a temperature sufficiently high to cause the said applied coating to form blisters.

4. The method of preparing metallic molds for-casting metal consisting in coating the said mold with a varnish like material while the said mold is maintained at a temperature sufliciently high to cause the said applied coating to form blisters and then breaking many of the said blisters.

5. The method of preparing metallic molds for casting metal consistin in coating the said mold with a varnish li e material while the said mold is maintained at a temperature sufiiciently high to cause the said applied coating to form blisters and then mechanically breaking many of the said blisters.

6. The method of preparing metallic "molds for casting metal consisting in coating the said mold with a varnish like material being an admixture comprising evaporated cellulose pulp waste liquor and water while maintaining the said mold at a temperature sufliciently high to cause the said admixture to blister.

7. The method of preparing metallic molds for casting metal consisting in coating the said mold with a varnish like material being an admixture comprising evaporated cellulose pulp waste liquor and water while maintaining the said mold at a temperature of approximately 450 F.

8. The method of preparing metallic molds for casting metal consisting in coating the said mold with a varnish like material being an admixture comprising evaporated cellulose pulp waste liquor and water while maintaining the said mold at a temperature sufiiciently high to cause the said applied admixture to blister and then mechanically breaking the said blisters.

9. A metal mold for casting metal having a surface coated with nonmetallic blisters.

10. A metal mold for casting metal having a surface coated with nonmetallic broken blisters.

vlSi ed at Philadelphia, county of Phila- 

